Now smaller and quieter, a ventricular assist device offers a more versatile bridge to heart transplant.
Stronger and healthier: Jason Dale, with mom Dorothy and sister Pam, after he received an axial flow left ventrical device from Washington university physicians at Barnes-Jewish Hospital.
HIS HEART WAS FAILING. In May 2005, 31-year-old Jason Dale came to Barnes-Jewish Hospital gasping for breath and barely able to walk 20 feet. But by June 22 — three weeks after getting a new kind of mechanical heart assist device — he looked completely healthy. A small motor in his chest cavity was helping his heart circulate blood throughout his body.
“I feel 100 percent better,” Dale says. “At lunch, I walked from here to Applebee’s, about three blocks away, and I felt great.”
Before the surgery, Dale’s heart was expelling only about 10 to 15 percent of its blood, compared to a normal heart’s 60 percent.
“We knew that Jason wasn’t going to do well without a transplant,” says Dale’s cardiologist, Gregory A. Ewald, MD, associate professor of medicine and director of the heart failure and cardiac transplantation section. “With him facing a potentially long wait for a donor heart, we decided to implant the assist device to keep him going and get him stronger.”
Dale received an axial flow left ventricular assist device, becoming the first person in Missouri to receive this “second generation” heart assist device. Nader Moazami, MD, assistant professor of surgery and chief of cardiac transplantation, performed the surgery.
Unlike a total artificial heart, which completely replaces a patient’s own heart, ventricular assist devices (VADs) are implanted alongside the heart. VADs can support the right, left or both ventricles.
For Dale, a left VAD (LVAD) was a good choice. His right ventricle, although weak, retained enough function for the relatively easy task of moving blood through the lungs. The LVAD would connect to his inadequately functioning left ventricle and pump blood up to his aorta to supply blood to the rest of the body.
Most current LVADs are large and heavy. Dale is not a big man, and the devices wouldn’t fit him. Fortunately, the School of Medicine had just been approved to participate in a multicenter phase II clinical trial of the HeartMate II, one of several smaller, streamlined devices.
Dale’s new heart pump weighs in at 12 ounces, about one quarter the weight of some predecessors. And while older LVADs are about the size of a large alarm clock, this device is as small as a D battery.
But its most significant innovation is in how it moves blood. “The first generation LVADs have a diaphragm or plate that draws the blood in and pushes it out,” Moazami explains. “The new devices are axial flow pumps — they have small blades that rotate on bearings and push the blood through in a continuous stream. They are a leap forward from what we’ve had in the past.”Since axial flow pumps don’t beat, patients with the devices may have only a minimal pulse from their own hearts or no pulse at all. “If you listen to my chest you hear a humming sound,” Dale says. “They say the older ones make a clacking noise you can hear a hundred feet away.”
Twenty-five years ago, at age six, doctors diagnosed Dale with acute lymphocytic leukemia. While they cured his cancer using chemotherapeutic agents, they also warned his family that the drugs could damage his heart.
With rapid advances taking place in cardiac medicine, Dale wouldn’t have been far from the truth if he had thought, “By the time I need to worry about my heart, they’ll have a cure.”
In the years he was struggling with cancer, the news was full of stories of the first attempts to implant artificial hearts as long-term heart replacements. In the early 1980s, William DeVries, MD, carried out a series of five implants of the Jarvik 7 artificial heart, a pneumatically powered, four-chambered mechanism that mimicked the activity of the natural heart.
For many years, medical complications thwarted efforts to make the artificial heart a permanent option for heart patients. Meanwhile, research began demonstrating the benefits of heart assist devices.
In 1994, the FDA approved LVADs for use as a “bridge to transplant.” Two years later, Dale was diagnosed with congestive heart failure. He was 22 years old.
Not long after this diagnosis, Ewald became Dale’s cardiologist. For more than eight years, Dale did well. “Jason was on typical medications for treating cardiomyopathy,” Ewald says. “His heart muscle wasn’t normal, but he felt good during that time.”
Then, in late 2004, Dale’s heart deteriorated rapidly. When he came to Barnes-Jewish Hospital in May, he was on intravenous dobutamine to improve his cardiac muscle contractions, but even so he wasn’t maintaining sufficient cardiac output. He was barely able to eat and had lost 20 to 25 pounds.
“Jason was identified as a candidate for an LVAD at the very same time we received approval to begin the clinical trial,” says Kim Shelton, RN, coordinator of the hospital’s VAD team along with Beth Kehoe-Huck, RN. “We put together and trained a VAD team for the new device within a week.”
A VAD team supports each patient who receives a heart assist device from the time he or she is admitted and follows up after the patient leaves the hospital. It includes anesthesiologists, perfusionists, intensive care and floor nursing staff, social workers, physical therapists and dietitians as well as cardiac surgeons and cardiologists.
Dale’s rapid improvement after the implantation pleased everyone on the team. “It was so good to see him getting stronger, eating well and feeling well,” Kehoe-Huck says. “He started walking very soon, going further and further every time.”
The pioneering surgery was noted when Dale was interviewed for a local newscast. Reveling in his moment of fame, Dale demonstrated the device’s battery packs and its controller, which is connected to the internal pump through a cable that runs through his abdominal wall. The heart pump is electrically powered, and when Dale is at rest, the controller unit is plugged into an
The clinical trial of the new heart assist pump will evaluate the device’s ability to keep patients healthy while they await a heart transplant and will look at the suitability of the device for permanent implantation in patients who are not good candidates for transplant.
Axial flow devices have been engineered to minimize the possibility of blood clots, and since they have only one moving part, they could prove more durable than the older devices. Two other brands of axial flow VADs are manufactured: the DeBakey VAD and the Jarvik 2000.
“With axial flow and diaphragm pumps now available and other devices in development, physicians have more options to choose from,” says Michael K. Pasque, MD, professor of surgery and member of the cardiac transplant team. “It’s a matter of picking the right one to match patients’ needs.”
Upcoming “third generation” assist devices will have no bearings to wear down; their rotors will be suspendedbetween magnets and will not touch the casing. Eventually, such devices may even eliminate the power cord coming out of the body and decrease the risk of infection.For Dale, the progression of technology hardly matters anymore. He looks forward to grilling in the back yard and fishing on lakes near his home. “I’m going to get my strength up. Hopefully, a miracle will come and I’ll get a matching heart,” he says. “Right now, I’m just glad they could help me. I thank God every day.”
Jason Dale’s LVAD assisted his failing heart for four months until he received a heart transplant on October 9, 2005.